Alternating-current motor.



PATENTED SEPT. 18, 1906.

M. 0. A.YLATOUR. ALIERNATING CURRENT MOTOR.

APPLICATION FILED JAN. 21, 1905.

lnvemifoi".

mcTrius CALaC'oun h y UNITED STATES OFFICE- \lAltlUS O. A. LATOUR, OFPARIS, FRANCE. ASSIGNOR TO GENERAL ELECTRIC COMPANY. A CORPORATION OFNEXV YORK.

ALTERNATING-CURRENT MOTOR.

Application filed January 21,

To all whom, it mag/concern:

Be it known that I, MARiUs C. A. Laroun,

1 a citizen of France, residing at Paris, France, l

' Figure 1 shows an alternating-current mobrush-lifting device, and

have invented certain new and useful Improvements in Alternating-CurrentMotors, 1 of which the following is a specification.

' My inventionrelates to alternating-current l motors of the commutatortype; and its object is to improve the operation and efiiciency of suchmachines. i As is well understood in the art, the armature-currents aregenerally a maximum at starting, and the currents induced in the ar 1mature-coils short-circuited by the brushes i are much greater atstarting than when the i motoris up to speed,bothbecause themotorcurrents and the resultant fields are stronger at starting and alsobecause there is present i no electromotive force due to rotation whichmay serve, to reduce the amount of short-circuited current. In order toprevent undue heating of the brushes and commutator at. starting, it isnecessary to provide a large brush contact-surface to carry the heavy ishort-circuited currents. When the motor is up to speed, this largebrush co'ntactsurface is not required and produces unnecessary lossesdueto the excessive brush-friction. l my invention I provide a novelarrangement of brushes, whereby sufficient brush contact-' surfaceisafforded at the start for satisfacto rily handling the .startingcurrents with 1 means for reducing thebrush contact-surface as the motorspeeds up, thereby eliminating losses due to unnecessary brush-friction.My invention consists in providing auto- 1 matic means for lifting aportion of the brushes out of engagement with the commutator withoutchanging the circuit connections of the motor as the motor speeds up. 1My invention will best be understood by i reference to the accompanyingdrawings, in i whichtor with brushes arranged in accordance with myinvention. Fig. 2 shows a detail of the Fig. 3 shows a del 4 l tailofthe controlling means for the brushlifting device.

' In Fig. 1, A re resents the armature, and

The field is provided with field-coils f, which may be of thedistributed or concentrated 1 type. The arrnature' is provided with thel Specification of Letters Patent.

- merely reduces the number of.brushes in each set, thereby diminishingbrush-friction and losses without changing the circuit connecti one ofthe machine.

One sui table construction of the electromagnets is shown in Fig. .2, inwhich the core (1 of the magnet D carries a spindle d, at the lower endof wh ch is secured the brush B,

vertically movable in the inclosing box or casing F. :The spindle dcarries a collar or washer (1, against whichbears a compres sion-springG. This spring tends to lift the core (1 and brush B", while the coil Dwhen en ergized tends to ull the core (1 downward,

forcing the brush against the commutatorsurface. Thus ifmeans areprovided for energizing the coil D at the start the brush B may be heldin engagement with the commutator, and if the coil D is denergized asthe motor speeds up the spring B willlift the brush B away from thecommutatoi', thereby preventing unnecessary brush-friction.

One arrangement for controlling coil D is shown in Figs. 1 and 3. Hrepresentsan arm 1pivoted at h t e spring I when the motor is at rest.The arm H carries a bridging memberJ, which is adapted when the arm H.is moved outwardly by centrifugal force to engage the contact j,carried by the collector-rings K.

Thus as the speed of the motor passes a redetermined limit thecollector-rings K wi be electrically connected by contact J. This actionmay thereby allowing the springs to lift the brushes B out of engagementwith the commutator.

Obviously, other arrangements for lifting brushes B at predeterminedspeed may bewithin the scope of my invention.

and held against thestop h be utilized to short-circuit the magnet-coilsD, as is indicated in Fig. 1,

What I claim as new, and desire to secure by Letters Patent of theUnitedStates, is

1. In an alternating-current, machine of the commutator type, means forautomatically lifting a portion of the brushes out of engagement withthe commutator without changing the circuit connections of the ma chinewhen the speed of the machine rises above a predetermined limit.

.2. In an alternating-current machine of the commutator type,electrically-controlled means for automatically lifting a ortion of,the'brushes out of engagement wit the commutator Without changing thecircuit connections of the machine when the speed. of the machine risesabove a predetermined limit.

3. In an alternating-current machine of the commutator type,electrically-controlled means for automatically lifting a portion of thebrushes out of engagement with the com- I mutator without changing thecircuit connections of the machine, and a centrifugal device controllingsaid lifting means.

4. In an alternating-current machine of the commutator type,electromagnets operatively connected to aportion of thecommutator-brushes and adapted when energized to hold said brushes inengagement with the commutator, and sprin s opposing the action of saidmagnets and ten ing to lift said brushes from the commutator, theelectri'callycontrolled brushes being arranged in axially alined setswith the other brushes so that the lifting of theelectrically-controlled brushes.

from the commutator does not change the circuit connections of themachine 5. In an'alternating currentmachine of the commutator type,electromagnet's opera tively connected to a portion of thecommutator-brushes and adapted when energized to hold said brushes inengagement with the Lranged in axiallv-alined sets with the otherbrushes so that the lifting of the electricallycontrolled brushes, fromthe commutator does not change the circuit connections of the machine.

6. In an alternating-current machine, a distributed armature-Windingprovided With a many-part commutator, a plurality of sets ofaXially-alined brushes bearing on said com-" mutator, and means forautomatically lifting a portion of the brushes of each set out ofengagement with the commutator when the speed of the machine rises abovea predetermined limit.

In witness whereof I have hereunto set hand this 17th day of January,905. v

MARIUS C. A.- LATOUR.

Witnesses HELEN Onronn, E. C. HOLLISTER.

